Roof Trusses installed on top of existing roof
I am looking for advice before engaging in paying for architectural/engineering services. So I know in the end I will need to pay for official approval of any design, but before doing all of that, and possibly wasting money, I want to make sure this expansion can be done. One issue I am having is determining will the existing roof support additional weight of the new construction.
The existing roof has 2×6 rafters, spaced 16″ O.C. The new room is perpendicular to the existing house, and the roof will be using trusses. That new roof will have a 3/12 pitch. the peaks of the existing and new roof will be at the same height. This means that there will be 4 roof trusses (27′ total width) that will sit on top of the existing 6/12 pitch roof. My question is, how do I determine if the existing roof will support the weight of the trusses?